>"The parameter to this message gives a specification of charging schemes acceptable. The client may retry the request with a suitable ChargeTo header."
>This line if present contains account information for the costs of the application of the method requested. The format is TBS. The format of this field must be in extensible form. The first word starts with a specification of the namespace in which the account is . (This is similar to extensible URL definition.) No namespaces are currently defined. Namespaces will be registered with the registration authority .
>The format of the rest of the line is a function of the charging system, but it is recommended that this include a maximum cost whose payment is authorized by the client for this transaction, and a cost unit."
>"The parameter to this message gives a specification of charging schemes acceptable. The client may retry the request with a suitable ChargeTo header."
https://www.w3.org/Protocols/HTTP/HTRESP.html
And charge-to is defined as
>"ChargeTo:
>This line if present contains account information for the costs of the application of the method requested. The format is TBS. The format of this field must be in extensible form. The first word starts with a specification of the namespace in which the account is . (This is similar to extensible URL definition.) No namespaces are currently defined. Namespaces will be registered with the registration authority .
>The format of the rest of the line is a function of the charging system, but it is recommended that this include a maximum cost whose payment is authorized by the client for this transaction, and a cost unit."
https://www.w3.org/Protocols/HTTP/HTRQ_Headers.html#z10